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This study aims to assess response of spectral UV radiation to different atmospheric and terrestrial factors, including solar zenith angle, ozone, cloud cover and albedo, in southern polar environment. For this purpose, 23260 individual spectra (300–363 nm), obtained by the B199 Mk-III Brewer spectrophotometer at Marambio Base, Antarctic Peninsula Region, over the period 2010–2020, were studied. A neural network model was developed to investigate the effects of the explanatory variables at individual wavelengths. SZA proved to be the most important parameter, followed by cloud cover, TOC, and surface albedo. The relative SZA effect is greatest at the shortest wavelengths, where a 1° decline in SZA results in a 6–18 % increase in UV irradiance (305 nm). Also TOC affects particularly the short wavelengths, while at 305 nm, a 10 DU decrease in TOC causes a 7–13 % increase in UV irradiance. In some seasons (e.g., 2011–2012, 2014–2015, 2018–2019), the large-scale ozone holes caused the UV irradiance at very short wavelengths peak in spring, whereas in other seasons (e.g., 2010–2011, 2012–2013), the maxima at all wavelengths were recorded in summer. The effect of cloud cover was strongest near the fully cloudy sky, and in summer months. Albedo affected the UV irradiance only weakly, its effect was strongest in early spring and late fall. [ABSTRACT FROM AUTHOR]

For spectroradiometers, the characterisation of their wavelength scale and spectral bandwidth underpins the quality of measured data substantially. This characterisation can be performed using metrology-grade tuneable monochromatic sources, which are currently available only in a few laboratories worldwide. Yet in numerous applications, only the in-field calibration is a feasible solution. We have designed and developed a tuneable and portable radiation source (TuPS) in the wavelength range from 300 to 350 nm for the in-field characterisation of Dobson spectrometers' wavelength scale and slit function, with standard uncertainties better than 0.02 nm in wavelength and with the bandwidth of emitted radiation smaller than 0.13 nm full width at half maximum (FWHM). The TuPS is designed such that only minor modifications of its optical system extend/shift its spectral range towards visible and near-infrared spectral regions and thus expand its application for characterisation of any spectroradiometers in the relevant spectral region of interest. [ABSTRACT FROM AUTHOR]